Frost never seemed to make its mind up as to where the town of Denton is. A lot of the rail shots use Leeds, but the line seems to electrify and de-electrify itself all the time, and occasionally jumps to Manchester. The map in the police station is Swindon tilted through 45 degrees (you can see the junction). One episode involved a lot of location shoots in a depot. I think it was Neville Hill, can anyone confirm this?
They used Longsight for filming about three or four years ago, but if you are thinking of the final episodelast month, I'm not sure where that was filmed.
I do remember a very clear scene of Wakefield Westgate in one episode from fairly early on.
Now, given that Denton is a suburb of Manchester, that it was a northern ITV franchise which filmed it and that so many of the scenes are recognisably from that area, it was a great shock to me to find out only a couple of months ago that in the series "Denton" is supposedly in the Thames Valley!!!
As for adverts, the VT one currently running depicting a student off home for the weekend to meet her boyfriend, supposedly representing an Euston - Manchester journey, is particularly interesting even without the refurbishment of the portals of Shugborough Tunnel...